how do some of the abiotic factors affect the distributiona dn abundance of organism in an ecosystem?
what are some techniques used to estimate the abundance (examples of some plants and animals measured)??

abiotic factors can be density dependent or density independent........the former includes food and the likes.....the latter includes sunlight,water etc.....density can be measured by QUADRATE METHOD....try searching this topic on internet......

actually food isn't an abiotic factor(for animals), though it is density dependent.
One abiotic factor that IS density dependent is space. You can only fit so many organisms into a finite space. Of course, food usually becomes a problem along with lack of space, kind of hand-in-hand.

What did the parasitic Candiru fish say when it finally found a host? - - "Urethra!!"

Why don't you find any information about the distribution of life in the air whereas it is already made up of the atmosphere of Titan, for biochemical material then and not even during the actual space mission, no, long time ago yet.

More explanation in my blog, post of 7/8/2006 2:42:46 AM, although don't look for clearly ordened writing. You may post your comments here also and leave your link, but say something you biologists, don't leave people in the darkness.

There are lots of abiotic factors affecting distribution and abundance of organisms. Abiotic meaning non-living. This will include temperature, pressure, light availabitlity/intensity, prsence/absence and the type of gas, available nutrients, moisture, pH, soil type, and lots more.

Ex. Considering microorganisms, many bacteria can be found in a typical garden soil, but in forest soil, there are usually more fungi. Forest soil usually has lower pH due to decaying leaves in forest floor. Generally, more fungi can tolerate a broader pH range than bacteria. Fungi are anaerobic so you can see very little of them in rice paddies or soil that contain high moisture (moisture instead of air is found in spaces between soil particles).

Ex. Notice why there are fewer grass/shrubs in a mature forest floor? Simply because sunlight cannot penetrate the forest floor making it difficult for small shoots and other small plants to grow.